Caffeine has a half life of roughly 2.5 to 4 hours. Which means that in that amount of time half of the caffeine will have been metabolized by your body. Caffeine only last a few hours depending on the consumption and your activity.
The amount of time spent playing video games has a negative correlation with academic performance (Gentile, D. 2004).On the other hand children also learn obsessive language and violent behavior from these violent video games which disturb child's mental status.
It is believed that acting out such violence as opposed to just viewing the violence causes the children to become more familiar with how to act out violence without consequences. On the other hand the makers of these violent types of media such as movies, video games and television argue that violent children are drawn towards these types of violent entertainment.